milage computer went blank ?

[immike@ix.netcom.com (michael mueller )]

  The trip/milage display in the dash of my 88 90 q. has been freaking 
out the last couple of days. Symtems: one day the display just froze up 
reading 19.5 no matter what . The reading even stayed on with car 
turned off. I've never seen numbers stay on the display with car off.
Well after car sat for about 2 or 3 hours the display worked just fine 
until today when the display just went blank for about 20 minutes while 
driving . any ideas? 
TIA 
     Mike Mueller
     San Jose
     88 90 q
     79 928 parting out [any interesting trades ?]